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| Clinic for Thoracic and Cardiovascular Surgery |
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21st February 2005
Background information VAD: alternatives and bridges to organ transplantation
37 years after the first heart transplantation, this intervention is now a routine occurrence at the Heart and Diabetes Center NRW. Whereas, when transplantation surgery began, one of the greatest problems was how to overcome organ rejection, nowadays it is the lack of available donor organs which moves scientists to seek viable alternatives to organ transplantation.
Ventricular assist devices bridge the wait until transplantation
With so-called mechanical circulatory support or 'bridging' systems, the waiting period until heart transplantation, on average 220 days, can be spanned or bridged. The VAD technology (ventricular assist devices) amounts to artificial support of the heart. VAD systems assume the pumping action of the left and/or right side of the heart. The body is thus once again supplied with sufficient blood/oxygen, stabilizing the condition of severely sick patients.
In some cases the pump is implanted underneath the abdominal wall, connected by a cable to a power supply and system controls outside the body. With some other systems the whole pump is located outside the body. The human body does not reject this pump as it does foreign human organs, meaning that patients do not require any immunosuppressive medication. Only blood coagulation is restricted so that blood clots are unable to form.
Which system is chosen depends on the medical indication, as well as the height and weight of the patient. Some systems enable patients to go home and wait for their transplantation in their familiar surroundings. This not only increases the patient’s quality of life at this difficult time; it also helps to keep the costs down.
The group of VADs comprises various blood pumps with different drive systems. In the last 30 years mechanical pumps which imitate the pulsation of a healthy heart (e.g. Thoratec, Novacor, Medos) have proved particularly successful. The disadvantage of these systems is their size, however, which cannot be reduced due to the necessary blood filling volume.
DuraHeartTM – the benefits of this magnetically suspended centrifugal pump are its small size and low energy consumption
Around the world scientists are currently researching to find new implantable, smaller systems. These miniaturized non-pulsatile VADs (recipients of these pumps have no pulse) can be divided up into two groups: axial pumps and centrifugal pumps. With the help of a rotor, a continuous, non-pulsatile blood flow is generated. The real advantage of these pumps is their small size and weight (the DuraHeart pump weighs just 540g), meaning that they can also be implanted in patients of slight stature. These systems also consume less energy, and their implantation is simpler and less invasive than that of conventional VADs.
DuraHeartTM is a magnetically suspended miniaturized centrifugal pump. Due to the magnetic suspension of the impeller rotating within pump, the system is free from wear and tear and extremely durable. DuraHeartTM can be used both as a bridge to transplantation and – especially – as an alternative to transplantation. The new DuraHeart centrifugal left-ventricular assist device was implanted for the first time worldwide on 15th January 2004 by Prof. Reiner Körfer, MD, Dr. h.c., Director of the Clinic for Thoracic and Cardiovascular Surgery at the Heart and Diabetes Center NRW, and his team of Senior Physicians, Dr. Latif Arusoglu, Dr. Ali El-Banayosy and Dr. Michiel Morshuis. The recipient was a 68-year old man. Since then, 11 patients have been treated with this system in Bad Oeynhausen.
LionHeart™ - a fully implantable assist device
LionHeart™ is a completely implantable left-ventricular assist device which was implanted for the first time – anywhere in the world – by Prof. Reiner Körfer, MD and his team of specialists at the Clinic for Thoracic and Cardiovascular Surgery within the Heart and Diabetes Center NRW, Bad Oeynhausen, on 26th October 1999. Unlike previous assist devices, the LionHeart™ system, developed by the American company Arrow International Inc., has no connection to an external power supply. The battery is sewn under the skin and is recharged from the outside by means of induction. This cable-free (and thus wound-free) power supply considerably reduces the risk of infection. The energy storage system within the body functions for 45 minutes without recharging, giving the wearer time to remove the charger belt and take a shower or a swim. A total of 12 patients have received this fully implantable system to date.
The CardioWest artificial heart replaces the diseased heart
CardioWest and AbioCor artificial hearts (total artificial heart or TAH) replace the human heart (to date the AbioCor has only been implanted within the framework of a clinical study in the USA). At the Heart and Diabetes Center NRW, 70 patients have successfully received the CardioWest artificial heart so far (first implantation February 2001), producing excellent results and the expectation of more to come.
The artificial heart consists of two polyurethane chambers which pump the blood into the small pulmonary circulatory system and the large systemic circulatory system. In in-patients, the artificial heart is driven by external compressed air. Since October 2003 it has also been possible to combine the CardioWest system with the mobile Excor drive. This drive unit was developed jointly with the company Berlin Heart and then modified at the Heart and Diabetes Center NRW. It is just as efficient as the CardioWest drive, but it is much smaller and more comfortable to use. The mobile drive unit enables patients to move around freely. The Heart and Diabetes Center NRW has already been able to discharge home 14 patients with this artificial heart, the first 14 worldwide.
Conclusion:
The ever-growing waiting lists for heart transplantation and increasing numbers of patients with terminal cardiac deficiency have taught us that human beings are capable of surviving for long periods with VADs and artificial hearts, and that their quality of life is vastly improved in the meantime. Our own and other international studies have also shown that these patients have a far more favorable physical constitution, and that their chances of surviving transplantation increase since perfusion of the inner organs, such as the liver and kidneys, is improved.
Prof. Reiner Körfer, MD, Dr. h.c.: “Despite all their advantages, these technical systems are unlikely to render organ transplantation from person to person superfluous. Nevertheless, with these systems the overall situation for people with severe heart disease is undergoing general improvement.”
(as at: February 2005)
Heart and Diabetes Center NRW
University Hospital of the Ruhr-University of Bochum
Press Office and PR
Anja Brandt M.A.
Georgstrasse 11, D-32545 Bad Oeynhausen
Tel: +49 5731 / 97 1955
Fax: +49 5731 / 97 2028
E-Mail:  abrandt@hdz-nrw.de
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